1. Field of the Invention
The present invention relates to a method and apparatus capable of accurately measuring the temperature of the front surface, rear surface, and/or inside of a substrate. More specifically, the present invention relates to a method and apparatus capable of accurately measuring the temperature of the front surface, rear surface, and/or inside of a substrate by using the interference phenomenon of low-coherence light and to an apparatus for treating substrates for devices which uses those method and apparatus.
The term “device” as used in the present specification means to include electronic and/or mechanical devices. Thus, in the present specifically, the term “device” is used in the meaning including electronic devices (semiconductor devices, liquid-crystal devices, organic EL devices, and the like) and very small devices such as the so-called micromachines.
2. Related Background Art
When a physical and/or chemical treatment is conducted on a variety of substrates, e.g., from silicon, accurately measuring the temperature of the front surface, rear surface, and/or inside of the substrate is very important from the standpoint of accurately controlling properties and physical characteristics of the product which is to be obtained by the treatment.
For example, in the field of fine processing based on lithographic technology in the field of semiconductor processes and micromachines where surface treatment methods are presently widely used, the treatment employing gas-phase reactions (for example, physical vapor deposition (PVD) and chemical vapor deposition (CVD), which represent deposition processes, and etching, plasma treatment, and heat treatment such as annealing) are frequently used.
In the field of devices, including electronic devices, primarily semiconductor devices and liquid-crystal devices, which have to be produced by presently available semiconductor processes, and micromachines, the requirements placed on quality improvement of the electronic devices which are the resultant product created a demand for multilayer structures and quality improvement in each of thin films constituting the device. Usually, actual products obtained in those thin film formation processes are extremely frequently affected by temperature. For this reason, the importance of temperature control in the outermost surface layer of the substrate or multilayer structure, which is to be treated, increases and cannot be underestimated.
For example, in processes using plasma, the outermost surface layer of the substrate to be treated, is irradiated with heat from plasma. In this case, it is clear that there is a difference between the outermost surface layer and rear surface of the substrate. Measurement methods employing resistance thermometers or fluorescent thermometers measuring the temperature of the rear surface of the substrate have been employed as temperature measurement methods for measuring the temperature of the surfaces.
However, In the above-described conventional processes, it was very difficult to measure directly the temperature of the outermost surface layer of the substrate due to restrictions placed by the structure and operation principle of the apparatus.